Potential of Mesenchymal Stem Cell Enriched Adipose Tissue Grafting for Contour Deformities of Face

Abstract

Soft tissue augmentation is required for contour deformities of the face. These contour irregularities of face frequently occur as a result of congenital disorders, acquired diseases, and traumatic and developmental deformities. Allogenic fillers such as Hyaluronic acid (HA) and autologous tissues such as dermal grafts, dermo-fat grafts and fascial grafts are suitable options to treat these deformities. Similarly, reconstructive surgery using pedicled or free flaps is the key reparative option for filling of large contour defects. All these autologous options, however, produce considerable donor site morbidity and there are certain limitations of using these options, including difficulty in fine contouring, graft resorption, and infection. Human fat tissue, being an autologous tissue source, has gained scientific attraction due to advantages such as abundant supply, availability in most patients, no immunogenicity and risk of infectious diseases. Although adipose tissue grafting is a well-known technique to correct contour irregularities, the lack of longevity and consistency of fat grafts remains a major problem in this field. In order to solve this problem of re-absorption of transplanted fat, other methods may help. The current study has used one such method to overcome the issues of re-absorption of transplanted fat. Human adipose tissue is a rich source of regenerative cells including adipose tissue derived stroma (stem cells) (ASCs). Recent animal studies have supported the role of ASCs as regenerative cells. ASCs have similar characteristics as mesenchymal stem cells (MSCs) isolated from other sources such as bone marrow, cord blood and cord tissue. The high number of ASCs in adipose tissue (as compared to bone marrow), significantly high proliferative potential and ability to differentiate into tissues of multiple lineages make these cells superlative candidates for tissue engineering and regenerative medicine applications. 2 Stromal vascular fraction (SVF) of adipose tissue that contains low number of ASCs can easily be expanded in vitro to increase ASC number and to get a pure population of ASCs. In the current study, patients with contour deformities of face requiring soft tissue augmentation were enrolled consecutively. Patients giving consent for traditional fat grafting underwent fat harvest, preparation and transfer on the same day (Conventional group). Patients giving consent for ASCs enriched fat transfer underwent fat harvest two times (Stem cell group). Adipose tissue was harvested with syringe aspiration in both groups and processed with gravity and filtration. In stem cell group, samples harvested on day one were used to isolate and expand ASCs. ASCs were isolated and culture-expanded using good manufacturing practice (GMP) grade reagents in a certified laboratory approved by the Institutional Review Board. After 2 weeks, the patients in Stem cell group again underwent fat harvest. This time prepared fat was enriched with ex vivo expanded ASCs and was transferred to recipient site. Prepared fat was injected throughout layers of tissue, till visual clinical symmetry with the opposite side was achieved. Number of fat grafting sessions and volume injected were noted. Both subjective and objective assessments were performed and complications were also noted. The mean (SD) age of patients was 25(9) years with 26(70%) females. Most common indication for fat grafting was Idiopathic Hemi-facial Atrophy in 19(51%) patients followed by congenital craniofacial microsomia in 9(24%), post traumatic deformity in 7(19%) and post infective deformity in 2(5%) patients respectively. Fat was harvested from the abdomen in 25(68%) and lateral thighs in 12(32%) patients. 3 Mean (SD) soft tissue thickness 72 hours and 6 months after first fat graft session in conventional group were 18.63(7.8) and 12.88(6.21) mm respectively whereas mean (SD) soft tissue thickness 72 hours and 6 months after the fat graft session in stem cell group were 23.62 (8.47) and 22.61(8.63) respectively. Mean (SD) percentage reduction in soft tissue thickness in conventional group and stem cell group, 6 months after the first graft session, was 30.77(13) and 5.03(3.39) respectively. Patient assessment scores were 2.52(0.521) in conventional group and 4.25(0.68) in stem cell group respectively. In patients undergoing ex-vivo expanded ASCs enriched fat graft, there was minimal decrease in soft tissue thickness of treated area six months post operatively and patients were highly satisfied with the outcome with the single session of the ex vivo expanded ASCs enriched fat graft. In conclusion fat grafting is safe and effective technique for correction of facial contour deformities. However the procedure needs to be repeated multiple times due to significant re-absorption. Beneficial effects of the use of ex-vivo expanded ASCs enriched fat grafting in terms of improving clinical outcome, has a potential to alter the current treatment paradigm of fat grafting for soft tissue reconstruction. In addition this technique will open new avenue for reducing the overall cost of procedure by reducing the number of sessions.